Suspension assemblies for bus and coach rear drive axles typically comprise four air springs, also known as “bags,” spaced at four separate locations to support the frame of the bus or coach on the axle. Such assemblies usually have two lateral tubes that connect the air springs from side-to-side and two fabricated I-beams, which connect the axle to these lateral tubes. The lateral tubes are welded to the I-beams. Welds are placed either on the top and/or bottom of the tubes at the intersection of the tubes and the I-beams.
The intersection of the I-beams and the tubes is subject to significant stress as part of the vehicle suspension. Consequently, the welds in these areas are also subject to significant stress. Due to the difference in geometry between the tubes and the I-beam, welds at the top and/or bottom surfaces of the lateral tubes serve as stress risers. Moreover, heat from the welding process may change the material properties at the location of the weld, weakening the strength of the material. This combination of stress and weakened material may shorten part life.
A need therefore exists for a suspension assembly that avoids the weld problems that occur at the intersection of the tubes and the I-beam.